This invention relates to new types of cationic quaternary ammonium emulsifier formulations for producing stable oil-in-water micro-emulsions. More particularly, the invention is directed to aqueous emulsions for depositing ("exhausting") or distributing hydrophobic films onto pre-washed surfaces as a substantially continuous film.
The emulsion droplets of cationic systems of the type employed in the present invention carry positive electrical charges so that the emulsified oil tends to be attracted to surfaces such as paper, fabric, or painted metal, these surfaces being normally negatively charged when in contact with water. As a result, the oil is exhausted, or "plated" onto the surface, creating an oily, substantially continuous hydrophobic film.
The phenomenon described has applications in several areas. For example, it is often desired to coat mops, wiping rags or doormats with oil so that dust and dirt will adhere. This effect is easily achieved by emersing the articles in an emulsion containing positively charged oil particles. The oil leaves the aqueous phase and deposits onto the fibers of the article treated.
Another important commercial application of the principle described is to use the emulsion system as a "rinse aid" in the so-called "spray-waxing" of automobiles. The end effect sought is to form a continuous, hydrophobic, water-repellant film on the car surface after the main wash cycle has been completed. The water left on the surface in the final rinse is caused to dissociate to form beads that can be blown off with the aid of an air jet. The vehicle surface is left essentially dry and clean, obviating laborious hand-wiping. It is known in the art how to produce emulsions suitable for the specific automotive application described. The advantages of cationic emulsifiers have also been recognized, and various types have been proposed in the prior art. Among these are the following:
______________________________________ U.S. Pat. No. ______________________________________ 1. Fatty amine salts Chestchowski 3340063 Holbus 3518099 2. Alkoxylated fatty amines Clark 3222213 3. Monofatty imidazoline Clark 3222213 4. Monofatty imidazoline Johnson 3583051 salts 5. Monofatty quaternary Clark 3222213 ammonium chloride 6. Difatty quaternary Atherton 3497365 ammonium chloride 7. Difatty alkoxylated Clumpner 3658718 amidoamine quats ______________________________________
The preparation and the properties and comparative features of various emulsion systems, including systems broadly of the general class involved in the instant case, are described in U.S. Pat. No. 3,658,718, and the entire disclosure of that patent is specifically incorporated herein by reference, to the extent not inconsistent herewith.
Some prior art emulsifying systems produce milky, opaque emulsions of petroleum oils in water. These formulations have been found to lack desired stability. Clear, micro-emulsions which can be stored and diluted with no tendency to cream out are preferred. The exceedingly small "droplet" size in such emulsions also results in more uniform distribution of the oil film over the car surface, ensuring improved beading and more ready removal of the rinse water film.
In order to achieve such clear emulsions, prior researchers and formulators have resorted to the supplemental addition of alkoxylated (nonionic) compounds. Thus, Atherton U.S. Pat. No. 3,497,365 teaches the use of blends of difatty quaternaries and ethoxylated amines; Clark U.S. Pat. No. 3,222,213 recommends that the monofatty imidazolines be blended with ethoxylated tallow amines; and Clumper U.S. Pat. No. 3,658,718 incorporates ethylene oxide groups into the emulsifier molecule itself.